No, not at all. In the case of cars with ICE the biggest challenge is still mechanical -- mostly related to environmental protection standards. To keep a BMW M5 Euro5 compliant you have to go a _long_ way. If you mean that you use software to design these cars then well, yes, I can agree. But the onboard software is still a very-very small part of the challenge.
(Ask somebody who's actually in the car industry, especially if he's in the higher-end market, like someone from AMG, BMW M, etc.; just the cooling of these things is an art.)
In the case of Tesla, things are slightly different, but not that much. The big thing here is the reliable electric motor, which -- also according to Tesla marketing -- is simple compared to an ICE, but in reality it's a big challenge to manufacture because high-powered electric motors need to be manufactured with incredible precision, otherwise they break quickyl and often.